Systems for enhancing vision at night have been developed for military use, in particular, and usually comprise an infrared imaging device for producing a black and white television image. The differences in infrared radiation from objects in a scene lead to different responses so that there is sufficient contrast among different objects to produce clearly visible images. Some details, however, are not apparent in an infrared image; e.g. there may be no contrast between the letters and the background of a highway sign. The warm objects in a scene can result, as matter of choice, in either light or dark images according to the mode of electronic processing which is used. Such black and white images are useful in certain applications, particularly when being interpreted by trained observers.
It is desired to provide a night vision system which is not limited to trained observers but which may be readily used by the general public. For example, the operators of automotive vehicles or aircraft or water craft may benefit from night vision systems which allow viewing objects or events which are not visible to the unaided eye. In such applications, however, it is useful to recognize colors in the scene, particularly colored lights which are characteristic of traffic signals, vehicle directional or brake signals, navigation markers and the like. The colors can also make highway signs legible. It has previously been proposed to use false color display techniques to distinguish between images discerned by infrared and visible light cameras to aid in image interpretation, however, that too requires trained personnel to interpret the images since they have unnatural colors which can be misleading.